VTR Vane-flow Test Rig
The introduction of variable geometry turbochargers, and the precision required in setting the sensitive mechanisms, created the need for a completely new flow setting machine to support the remanufacturing industry.
A VNT turbo needs to be set correctly so that it produces the correct boost pressure as the engine speed and power demand changes (VNT Turbo Operation). With incorrect boost pressure, both engine performance and emissions will suffer, and may result in an ECU shutdown putting a vehicle into limp-home mode.
The Turbo Technics VTR (Vane-flow Test Rig) is built to enable the measurement and adjustment of mass air flow through variable geometry turbochargers. The machines have been designed to include automatic compensation for atmospheric pressure, temperature, humidity and altitude, providing consistent results in all environments.
The first TT flow bench was built in 2002, based on the process used by Garrett. This became the basis for the Turbo Technics VTR which was initially designed to support an OEM remanufacturing programme commencing in 2010. This same process is now available to the remanufacturing industry, resulting in the production version VTR 200 introduced in 2012, followed by the VTR 100 in 2014.
The sensitive area of operation for the turbo is at low engine speed and power where the vanes are near closed. To ensure correct operation the flow needs to be calibrated with the vanes in a position close to minimum setting.
While the procedure will be different depending on the turbo type, the basic principle remains the same. Setting the VNT flow is a two-stage process, with the critical part being the positioning of the vanes at minimum flow, followed by tracking the movement up to full travel and checking for excessive friction.
The VTR works by flowing air through the turbo with the VNT mechanism in a set position and maintaining a constant pressure at the turbine with the rotor locked. Turbo specific templates are available for download from the Turbo Technics extensive database. These contain data for the correct flow and actuator travel figures for the relevant part number of turbocharger. The measured values are displayed on the screen in graphical and numerical form. Turbo Technics VTR machines have the capability to run turbos with electronic actuators and pneumatic actuators, including; vacuum, pressure and vacuum with position sensors providing voltage feedback.
In addition to the extensive range of TT supplied templates, customers are able to create their own templates.